Conventionally, as a method of forming particles in a nonaqueous medium, there are known a method of spraying a resin solution into a supercritical fluid (see Patent Documents 1 and 2, for example), a method of mechanically dispersing a heat-molten resin in a supercritical fluid in the presence of a microparticle dispersing agent such as an organic pigment or silicon oxide to form a microparticle of the resin, followed by pressure reduction to obtain a resin particle (see Patent Document 3, for example), and a method of mechanically dispersing a resin solution in a supercritical fluid in the presence of a microparticle dispersing agent and an activator to form a microparticle of the resin, followed by pressure reduction to obtain a resin particle (see Patent Documents 4 and 5, for example).
Patent Document 1: WO97/31691 pamphlet
Patent Document 2: WO95/01221 pamphlet
Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2005-107405
Patent Document 4: JP-A No. 2006-321830
Patent Document 5: JP-A No. 2007-277511